Electroresponsive device



June 12, 1934. A. A, EMMERLING ELECTRORESPONSIVE DEVICE Filed Dec. 18, 1931 VOLT/1 6f Inventor Anson A- Emma/Fling, by 006601.

His Attorney.

Patented June 1 2, 1934 1,962,898 ELECTRORESPONSIVE DEVICE Anson' A. Emmerling, Albany, General Electric Company,

New York Application December 1:8

N. Y., assignor to a corporation of 1931 Serial No. 581,820

3 Claims. (Cl 175-335) My invention relates to electro-responsive devices, and particularly to electromagnetically operated electro-responsive devices.

Electromagnetically operated electro-responsive devices, such as relays, indicating instruments, contact making voltmeters, etc., usually have but one magnetic circuit whose strength is varied in accordance with the condition to which the device is to respond. This change in strength is then made to produce suitable changes in the position ofan operating element.

In accordance with my invention.I provide a novel and simple electro-responsive device which operates on the differential strength, or flux, of a plurality of electromagnets having different electromagnetic characteristics. In a preferred form of my invention I oppose the forces produced by a pair of similarly energized electromagnets whose magnetic circuits have different magnetization characteristics. This may also be expressed by saying that the magnetic circuits have intersecting saturation curves.

An object of my invention is to provide a new and improved sensitive electro-responsive device.

Another object of my invention is to provide a novel electro-responsive device which makes use of the difierence in magnetic properties of different magnetic circuits.

In the drawing, Fig. l is a diagrammatic illustration of an applicationoi my invention to a contact making voltmeter which is used for controlling voltage regulating apparatus, while Fig. 2 is a set of magnetization curves for illustrating the principle of operation of my invention.

Referring now to Fig. 1, wherein 1 is a contact making voltmeter, embodying my invention, which is arranged to control the operation of a voltage regulator 2 in response to voltage changes on a circuit 3. Meter 1 comprises an operating element in the form of a movable armature 4 which is acted upon by a pair of electromagnets 5 and 6. These electromagnets have energizing coils '1 and 8, respectively, which areso connected that their energizations may be simultaneously and similarly controlled. In the illustrated embodiment this is done by connecting these windings in series across circuit 3, which happens to be an alternating current circuit. The magnetic circuits of magnets 5 and 6 contain materials 9 and 10 which have diflerent magnetic properties. be able to adjust the relative strength of magnets 5 and 6 I have provided variable resistance elements 11 and 12 that the normally balanced which are connected respectively in parallel with the operating coils '7 and 8 of the magnets.

It is immaterial to my invention, in its broader aspects, what the materials 9 and 10 of the magnetic circuits of my magnets are so long as these materials have magnetization, or saturation, curves which will intersect. Thus for example, I might employ ordinary soft iron for one magnetic circuit and air for the other, for the magnetization curve of a magnet with an air core is a straight line which must necessarily intersect any magnetization curve of iron. However, I prefer to employ ordinary soft iron which has a magnetization curve which is similar to curve 10 of Fig; 2 in one magnet and a ferromagnetic material, for magnet 5, which has a much more definite saturation point and a straighter and flatter curve beyond the initial saturation point than is. the case with :ordinary iron. A suitable term-magnetic material is a nickel and iron alloy and particularly the alloy known to the trade as Permalloy, consisting approximately'of 78 /2% nickel and 21%% iron. The magnetization curve of such a material is shown by curve 9 of Fig. 2. As will be seen from an inspection of curves 9 and 10, they intersect at point 0.

The operation of the illustrated voltage responsive contact niaking device, is as follows. Variations in voltage of circuit 3will cause similar variations in the energization of coils '1 and 8, but due to the differences in the magnetic properties of the magnetic circuits of these coils, a variable differential force will be applied to armature 4 because both magnets are oppositely acting on this armature. In order to make meter 1-act properly in response to voltage variations on circuit 3 so as to control regulator 2, I adjust resistances 11 and 12 so that when the voltage of circuit 3 is normal the fluxes produced by both electro-magnets are equal. As

shown in Fig. 2 this will be at point 0. If new :the voltage of circuit 3 should increase the'fiux of magnet 6 would increase along the curve 10 flux of magnet 5 will increase of Fig. 2. The result will be pulls of the two magnets will be changed, the pull of magnet 6 overcoming the pull of magnet 5 and causing armature 4 to be attracted to magnet 6. In a similar manner if the voltage,of circuit 3 falls below normal the pull of magnet 5 will become stronger than the pull of magnet 6 and armature 4 will move in the opposite direction. -'By providing armature 4 with suitable conof Fig. 2, while the along the curve 9 tacts 13 the proper circuits may be made and broken when the armature 4 is in its extreme positions, to cause a small pilot motor 14 to operate regulator 2 so as to restore the voltage of circuit 3 to normal. Regulator 2 may be of any suitable type and is illustrated as the well known induction type.

In order to compensate for the increased pull on armature 4, which takes place when the air gap between the armature and either one of the magnets decreases as the armature is attracted to this magnet, I provide suitable shunting resistances 15 and 16 which are controlled by contacts 1'? on armature '4. In this way, whenever the armature is attracted to one or the other magnets, a resistance is connected in parallel with this magnet coil thereby shunting a part of its current and weakening the pull of this coil so that when the two magnets are again equally excited the armature may be returned to its mid-position.

It is preferable to provide movable armature 1 with suitable biasing means, such as springs 18 for holding this armature in its mid-position when both magnets are deenergized. As a consequence of this arrangement, if the voltage of circuit 3 should fail for any reason, the armature will immediately go to its mid-position thereby stopping motor 14. It is therefore unnecessary to provide a low voltage relay with my regulating arrangement. Ordinarily, however, such a relay is necessary because with the ordinary contact making voltmeter when the voltage of the main regulating circuit falls the contact making voltmeter immediately. closes the contacts which tend to make the regulator raise the voltage of the circuit.

Although I have shown the coils 7 and 8 connected in series, it will be obvious to those skilled in the art that the same results could be secured by connecting them in parallel. All that is necessary being that they are both to be subjected to similar changes in excitation.

, which intersect, separate While I have shown and described a particular embodiment of my invention, it will be obvious to those skilled in the art that changes and modifications may be made without departing from my invention and I therefore aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In combination, a pair of electro-magnets, a movable armature arranged to be subjected to opposed pulls by said magnets and to move toward the magnet producing the greater pull, said electromagnets having magnetic circuits with intersecting magnetization curves, and separate magnetizing windings for each of said electromagnets.

2-. In combination, a movable armature, a pair of electromagnets for producing opposed pulls on said armature, means for simultaneously energizing said magnets in such a manner that the pull of one of them on said armature exceeds the pull of the other whereby said armature moves toward the former, and means responsive to said change of position of said armature for relatively decreasing the pull of the stronger magnet with respect to the pull of the weaker magnet.

3. In combination, a movable armature, a pair of electromagnets for producing opposed pulls on said armature, said magnets having magnetic circuits having magnetizing characteristics magnetizing windings for each magnet, and means responsive to a predetermined motion of said armature toward either magnet for connecting a resistance in parallel with the magnetizing winding of said magnet.

' ANSON A. MMERImG. 

